(a) Field of the Invention
The invention relates to the field of blow molded plastic bottles of the type commonly used to contain soda, each containing a separate base element.
(b) Prior Art
Plastic bottles, of the kind in which carbonated beverages are commonly sold, are being used with increasing frequency. The plastic containers are used in lieu of glass containers. The plastic containers are typically, but not necessarily, formed of a blow molded polyester bottle, which has a rounded bottom and is therefore unstable for storage purposes. The rounded bottom is necessary in order to be able to achieve efficient manufacture of structurally satisfactory plastic bottles, so that it is necessary to stabilize the bottle, so that it can easily be stored in upright position, with a separate base element which has a flat bottom and is typically adhesively glued to the bottom of the bottle element.
It frequently occurs that a bottle is not satisfactory for filling, because it does not pass the applicable quality control tests. Some reasons why bottles are not usable are that they leak (in the manufacturing process, they are checked with a leak detector), the labeling machine has not applied or has misapplied the label, the bottle neck is not formed properly or the bottle is mounted in the base cup at a crooked angle. If any of these situations occur, the bottle is rejected and will not be reused.
For economic reasons, it is desirable to be able to recycle the unused bottle to recover the plastic for its scrap value.
Various machines have been attempted to be made for automatically removing the base cup from the bottle, but to the best of applicant's knowledge, none of these has been successful. Therefore, in many, if not most, bottle factories, the base cap is removed from the bottle by hand, with the operator digging his or her fingers in the space between the upper edge of the base cup and the bottle and simply pulling the base cup off, shearing the adhesive glue spots which fasten the bottle to the base cup. This is a very tedious and difficult task for the average factory worker; it is not desirable work and is slow and expensive to achieve. Furthermore, when the base cup is finally removed manually, the bottle itself is often wholly or partially crushed and is therefore not easy to cut into sections. It is desirable to cut the bottle into sections, since the resin which is not contaminated with glue spots or a label is more valuable and more easily reused than the resin which is contaminated with a label or glue spots. However, the crushed bottle is very difficult to cut automatically and rapidly into sections, and therefore another problem in a plastic bottle factory is the problem of developing an adequate cutting mechanism for cutting various sections from the bottle.